Aliso Canyon Update

SCAQMD's responses to the Oct. 23, 2015 discovery of a massive leak in SoCalGas's well SS-25, one of 115 wells in the company’s Aliso Canyon underground natural gas storage facility. The well was sealed Feb. 18, 2016.

Recent & Upcoming Activities

SCAQMD staff are working to implement the $1 million health study of the impacts of the Aliso Canyon gas leak incident. For more information, visit the Health Study page.

Northridge East Neighborhood Council meeting – Oct. 17, 2018
SCAQMD staff were invited to the Northridge East Neighborhood Council meeting to present an update on the draft Request for Proposal (RFP) for the health study. The public is invited to submit comments on the draft RFP to by Oct. 21, 2018, 11:59 p.m.

  • Presentation (PDF) – "Update and Draft Request for Proposal, Research Study to Investigate Health Impacts of the Well Rupture at Aliso Canyon"


Aliso Canyon Natural Gas Well Sealed

Southern California Gas Company (SoCalGas) operates the Aliso Canyon natural gas underground storage facility at 12801 Tampa Avenue in Northridge, CA 91326. On October 23, 2015 SoCalGas discovered that Well SS25 used to inject and withdraw natural gas from the underground storage reservoir at their Aliso Canyon facility was leaking.  On February 18, 2016, the California Department of Conservation, Division of Gas and Geothermal Resources (DOGGR) provided notice to the public confirming that Well SS25 at the Aliso Canyon Gas Storage Facility had been successfully sealed.

South Coast Air Quality Management District (SCAQMD) and California Air Resources Board (CARB) staff jointly developed a set of criteriaLink to external website. to determine when air quality in the surrounding communities of the Aliso Canyon facility has returned to typical conditions -  a checklist to determine when the air quality is no longer being impacted as a result of the leak.  Click on the following links for information about:

SCAQMD staff continues to observe and monitor operations at the Aliso Canyon facility and the surrounding community and to conduct ambient air measurements both within the facility and offsite in Porter Ranch and surrounding communities. 

Additional Air Monitoring and Inspection Activities

On July 31, 2017, SoCalGas (SCG) resumed natural gas injection operations at its Aliso Canyon storage facility.  As one of the conditions for resuming injection activities, aerial measurements of methane emissions from the facility were conducted by a third party contractor earlier that week. Airborne surveys on July 27 and August 3, 2017 revealed the presence of increased methane emissions from the northwest portion of Aliso Canyon.

In response to this finding, starting on July 28, 2017, SCAQMD staff from the Office of Compliance & Enforcement and Atmospheric Measurement were dispatched to investigate the cause of these elevated aerial measurements, and mobile methane surveys resumed within and outside of the SCG property line, to include within The Termo Company (Termo), and in the surrounding communities. While inspectors and atmospheric measurements staff detected, identified, and verified repairs of specific leaks from various components at both Termo, and SCG, so far, no obvious emission sources associated with renewed injection operations have been detected by SCAQMD staff.  

Mobile surveys in Porter Ranch and other neighboring communities have consistently shown methane readings close to typical ambient levels. SCAQMD will conduct additional mobile surveys and follow-up inspections at both Termo, and the SCG Aliso Canyon facility, and in the surrounding communities. Mobile methane survey results and updates are posted on our website.

Final Air Monitoring Results

An Executive Summary and a final technical report summarizing the air monitoring results from all fixed site and mobile measurements conducted by CARB and the SCAQMD between October 2015 and June 2017 have been prepared:

Compliance/Enforcement Activities

News Releases


Report odors similar to the sulfur (rotten egg) smell of natural gas to 1-800-CUT-SMOG (1-800-288-7664) or through the On-line Complaint System.  If  you otherwise believe there is a problem related to natural gas, please also contact SoCalGas at 1-800-427-2200.

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